Building a wooden house yourself, what should be considered?

The minimum values reflect the energy saving ordinance calculation (without it, it’s not possible either), you can’t just say that flatly. A log cabin house doesn’t work without additional insulation.
Fire protection regulations are a matter for the federal states – but for a single-family house, it’s not particularly decisive whether the house is made of wood or stone.

As a rule, log cabin houses (wood thickness only 40-70 mm) are garden houses and do not meet the requirements for houses as a main residence.
These huts/garden sheds in the "log cabin look" with little wood are colloquially often mistakenly called log cabins.

High-quality residential log houses built in true log construction have nothing in common with these inexpensive log cabin imitations. In real climate-friendly log houses (log beams 275 mm) for living, no insulation with foils needs to be installed. The minimum values according to the energy saving ordinance calculation are met.

Many people still don’t know what they are building, but many already know the price very precisely. "Quality remains when the price is long forgotten." Quote H. Gordon Selfridge

Why do log cabin houses look so cheap at first glance? They have a very low wood content and a lot of cheap thermal insulation.

Real climate-friendly log houses with a very high wood content have thick massive wooden walls with beam thickness between 230 mm and 275 mm depending on manufacturer and location. We chose 275 mm. The house was built in 2016. We would always build like this again.